Is It Liquid Or Solid?

In Drilling Fluid: The Lifeblood of the Well you can read about Visplex*, a substance used in the drilling fluid that transports cuttings from the bottom of a borehole to the surface. Visplex has the unusual property of being able to change form. When it is at rest it is a gel. When it is in motion it becomes a free-flowing liquid.

A mixture of cornstarch and water also changes viscosity depending on whether or not it is agitated, but in a different way. Investigate for yourself and see how it behaves.

Tools & Materials

To conduct this experiment you will need:

• 1 pound (500 gram) box of cornstarch
• About 1 2/3 cups (400 milliliters) of water
• Mixing bowl
• Variety of small tools and objects for exploring such as:
• Small coin
• Small rock
• Popsicle stick
• Metal spoon
• Plastic spoon
• Notebook or pad and pencil, or a computer to record your observations.

The Experiment

Here's what to do:

1. Make a cornstarch and water mixture. Pour the cornstarch into your bowl and then add the water. Mix the two together by lifting the mixture from the bottom of the bowl to the top with your fingers until there is an even consistency.
2. Play with it. Use your hands, a spoon, a stick...
3. Make note of properties such as size, shape, texture, weight, hardness.
4. Consider these questions, and test them out for answers:
   • How does it behave when you stab it quickly with a finger?
   • How does it behave when you rest a finger lightly upon it?
   • Can you pick it up?
   • Can you break it?
   • Can you pour it?
   • When does it behave like a solid?
   • When does it behave like a liquid?
   • Can it suspend a solid, such as a small rock, a coin, or a piece of wood? Do these objects float on the mixture or sink into it?
5. Record your observations in words and drawings. It's good to work with a partner and take turns playing and recording. It's difficult to write or type with this gooey mixture all over your hands.

You might also want to have a look at what we found.

*Mark of Schlumberger